Yearly Archives: 2014

The Evolution of an Outside Shot

So, in order to not get beat up under the basket, I must have a reliable outside shot.  I never needed an outside shot before, as I was always the guy banging around under the basket.  Now that I’m old and feeble, this is a real good way to get hurt (ask me how I know).  In the good old days, I might get bruised up in a game, but would be ready to do it again the next day.  Now if I get bruised up, it might be several weeks before I can play again!  I can remember remarking to my wife that “I can tell I’m getting old; it used to be that I took a couple of aspirin after a big game for relief from bruises, but now I find myself taking a couple of aspirin before the game”.  And this was when I was on the uphill side of 40! ;-).

OK, so I know I need to develop an outside shot – but how hard can it be?  I have the basket and backboard installed, and I have my double-height basketball escape-prevention mechanism in place.  All I had to do (I thought) was go out and shoot a few baskets and voila!  3-point shot!

Not

Being the scientific type, I started out by measuring my 3-point shooting performance over time using Excel, and was encouraged somewhat to see steady progress in my shooting percentages over time.  However, after doing some inet research I discovered that my shooting percentage from 3-point land was about half what was required for reasonable performance in competition.  About the best I could do was somewhere in the 30’s to 40’s (on a good day).  This sounds pretty good until you discover that most experts agree that one’s percentage in competition is about half the practice percentage, and 30’s to 40’s in competition is considered the minimum requirement for a productive member of a team – oops!!

3-Point shooting percentages taken over a 6-week period

3-Point shooting percentages taken over a 6-week period

After a while, it seemed like I just wasn’t getting any better, no matter how hard I tried or how much I shot (and by this time, I was shooting several hundred shots per day).  Also, I was concentrating entirely on 3-point shooting, and my other shots from shorter ranges (including at the foul line) sucked even worse.  So, I did what I have done every time I have been faced with a hard problem – I tossed out all my assumptions and started researching “the perfect basketball shooting form”.  In the process, I ran across a series of videos created by Arthur Jackson of “One on One Basketball” fame. The videos are at http://www.monkeysee.com and go from the correct shooting stance, proper shooting mechanics and follow-through, and typical mistakes.  The first video in the series is “How to Shoot a Basketball“.

After viewing the videos and comparing them with video from some of my practice sessions, I realized that my shot form was, well, shot.  I was going to have to start all over again and develop a shot from scratch.

The above video was shot in late August 2014 and shows the essentially two-handed shot style I had developed up to this point.  The following video shows the shot style I have developed a couple of months later, based on the Arthur Jackson video series.

 

BBall Wannabe

 

After selling my glider this summer, I decided to return to a sport I have loved all my life – basketball. The only problem is – at age 65 that seemed just a little bit optimistic, if not outright insane! I had actually tried a return to b-ball 10 years or so ago, but got dinged up in pretty short order and had to quit.

As a result of being fairly tall and strong in my misbegotten youth, I had never developed much of an outside game. My normal MO was to simply crash the basket and force up shots from inside 3 feet. As I discovered when I recently tried getting back into the sport, what worked at age 25 doesn’t necessarily work at age 60 or so. So, being the engineer I am, I analyzed the problem and came up with a different approach. My plan this time is to develop an outside game, allowing me to patrol the 3-point line and avoid injury by avoiding the area under the basket.

Of course, this implies the ability to actually score effectively from 3-point land, something I’ve never been able to do. I was going to have to start from scratch and develop a skill I’ve never had before – cool!

First things first; I needed a basket and backboard, and a place to put them. I had the place – a nice concrete apron in front of my garage, complete with retaining walls on three sides (and a loooonnnnngggg driveway on the 4th). Ordered the basket, backboard, and 2 basketballs online, and within a week or so I had the backboard and basket up and installed. The garage apron area was just large enough to accommodate a 3-point circle, with about 3 feet left over directly in line with the basket. Once the basket was up and leveled, I spray-painted a dotted-line 3-point circle (high-school dimensions – not pro!), and started shooting.

The first thing I discovered was that my looonnnngggg driveway ate basketballs at a prodigious rate (well, it didn’t actually eat them – just transported them into a different area code). Yet another engineering problem to solve. After considering and rejecting several different designs, my research led me to a kid safety outfit selling a 25-foot long, 3 foot high retractable driveway net. With the help of a really cool hammer-drill and a 3/4″ concrete bit, I was able to install this where the garage apron area necks down to the aforementioned long driveway, and (mostly) stopped basketballs from escaping.

The second thing I discovered was that ‘mostly’ wasn’t good enough – I was still getting bball escapees on a regular basis, even with the retractable driveway guard in place. So, I ordered a second driveway fence and installed it on top of the first one – problem solved (mostly mostly). I still get escapees on occasion, but they have to work a lot harder to get away now ;-).

 

 

Flap Handle ClearNav Remote Caddy Done! (I hope)

John tells me that the latest and greatest flap handle ClearNav remote caddy version is alive and doing well in his glider.  The flap grip section fits over the metal flap control handle nicely, and the redesigned remote caddy section with its beefed-up quarter-turn fastener seems to be holding up OK so far.  The ‘caddy garage’ piece also seems to be working to hold the remote caddy in an out of the way place when not in use, allowing John to enter/exit the glider without worrying about damaging the caddy or breaking a cable.  Only time will tell, but for now it looks like I might be DONE!!!

Original flap grip replaced with ClearNav remote caddy

Original flap grip replaced with ClearNav remote caddy

Remote caddy detached from flap grip and connected to 'garage' piece mounted to instrument panel using one of the instrument screws

Remote caddy detached from flap grip and connected to ‘garage’ piece mounted to instrument panel using one of the instrument screws

I Need a Better Class of Pilot!

In our last episode of the Flap Handle Follies, I was sure I had all the bases covered.

  • Larger set-screws in grip – check!
  • 1/4 turn locking latch connecting flap grip to remote caddy assembly – check!
  • Rotatable remote caddy with spring-plunger detent every 10 degrees – check!

Unfortunately, one essential item for success with this version was missing from my checklist, and its absence spelled doom:

  • Non-gorilla pilot – check!

A few days after sending the latest version to John, I got an email with some photos and suggestions, and a few days after that I got my folded/stapled/mutilated flap handle assembly back – boy was I embarrassed!  What I had thought was a *brilliant* solution to a problem turned out to be not-so-brilliant when exposed to a pilot who expected things to go together in a particular way.  I had designed the 1/4 turn locking mechanism so the locking direction was opposite the normal “righty-tighty” direction because by doing so, the pilot’s normal thumb position on the remote caddy tended to hold the caddy locked onto the flap grip, as opposed to tending to unlock it.  Unfortunately, I had forgotten to mention this feat of brilliance to my friend, who expected everything to conform to normal lock/unlock conventions – oops!

Ah, well – it wasn’t a total failure, because we learned some things in the process:

  • The 3-piece assembly (flap grip, grip-to-caddy converter, caddy) was too long; John couldn’t reach the CN remote’s buttons with his thumb while his hand was comfortably placed on the flap grip.
  • The 1/4-turn locking mechanism was way too fragile (jokes about gorilla pilots notwithstanding)
  • The dimensions of the rectangular slot in the grip piece seemed to be just about right.

So, back to the drawing board yet again.  hunting through the forest of design possibilities for just the right combination.

  • Minimize or eliminate the grip-to-caddy converter to reduce overall length
  • Enlarge/strengthen the 1/4-turn locking mechanism (but keep the opposite direction actuation)

Minimizing or eliminating the converter piece required that I drop the caddy rotation feature.  This was kind of overkill anyway, as John had marked the correct (for him) rotation much earlier in the game;  I was trying to generalize his preference into something other pilots could use as well.   I just needed to think about the rotation feature as something ‘baked in’ to the design, rather than something pilot-adjustable.

Enlarging/Strengthening the 1/4-turn locking mechanism shouldn’t be too much trouble, as the latch parts were available in their own separate design files, so a simple scaling operation should do the trick there.  The only limitation on size being that the latching mechanism has to fit into the top of the flap grip and the bottom of the converter piece.

Based on my now extensive experience with printing parts on my PrintrBot, I also added the requirement that each part be printable in a way that preserves the quality of the mating surfaces.   I have come to understand that there is a right way and a wrong way to print parts; the right way result in very clean and smooth mating surfaces, while the wrong way results in ugly, bumpy surfaces that no amount of sanding can make right.  Fortunately, the combination of careful design and clever positioning of the part on the print plate seems (so far) to be effective.  The trick here is to make sure that parts are positioned so the mating surfaces are either perfectly parallel or perfectly perpendicular to the print plate; in either orientation the result is nice, clean surfaces.  In the case of the converter part, the mating surfaces aren’t parallel to each other, so it was placed vertically on the print plate so the larger mating surface (remote caddy interface) was perpendicular to the print plate, and the smaller (flap grip) surface was tilted 20 degrees from the vertical.  Near-vertical surfaces also print very well, so this resulted in both mating surfaces printing nicely, but the cost was a much longer printing time (2 -3 hours vs about 15 minutes!).

In the previous version, the thickness of the grip-to-caddy converter part was driven by the need for the caddy to rotate on the converter-to-caddy mating surface, which required that the converter have a hole deep enough to accommodate a reasonably sized axle post on the caddy part.  Eliminating the rotation feature allowed me to eliminate much of this thickness.  I still had the following requirements:

  • The caddy has to be rotated about 25 degrees CCW with respect to the fore-and-aft centerline of the flap grip, when looking at the top of the caddy. This value was measured from John’s marks on an earlier version.
  • The caddy has to be tilted vertically about 20 degrees with respect to the flap grip mating surface (again taken from John’s feedback).

To implement the ‘minimized’ grip-to-caddy converter piece, I went back to Autodesk 123d Design’s ‘sketch loft’ feature.  This is a very cool capability, and makes it (just) worthwhile to deal with 123d Designs many other ‘non-linear frustrations’ (see 2014/10/tinkercad-vs-123d-design-vs-meshmixer-pick-poison/).  I started with a 2D ellipse that matches the flap grip cross-section, and then added a 2D sketch of the caddy. Then I tilted and rotated the caddy sketch as defined above, and then ‘lofted’ the ellipse sketch into the caddy sketch – voila!

Now that I had the grip-to-caddy converter design worked out, all I had to do was to insert the scaled up 1/4-turn latching mechanism into the top of the grip and the bottom of the converter, and print all the parts.  Scaling and inserting the latch parts turned out to be pretty easy, as I already had all the latch geometry issues worked out from the time before, and all I had to do was use Tinkercad’s uniform scaling feature to ‘grow’ the latch about 150% or so.  After scaling the parts, I latched and unlatched them in Tinkercad a couple of times to make sure that Part A did indeed fit into Part B, and then simply copy/pasted them into the grip and converter designs.

There was one complicating factor; due to printing concerns, I decided to print the converter and caddy parts separately, and then screw them together using 2ea 4-40 screws.  I designed matching 2mm pilot holes in both the caddy and converter mating surfaces, and I added thickness to the bottom of the caddy so I could countersink sufficiently (about 3mm) to hide the screw heads below the bottom surface of the caddy.  However, when I got everything done, I wound up just gluing the parts together with gap-filling superglue from my local hobby shop, and this seemed to do much better than screws.

In summary, I was able to quickly design and implement a new flap-grip version with ‘baked-in’ caddy twist and tilt, and was able to get the caddy about 12mm (about 1/2 inch) closer to the flap grip than in the old design.

As an added amenity for the pilot, I decided to design and implement a ‘caddy garage’ so John would have a place to store the caddy when it wasn’t in use.  As part of the original testing program for the 1/4-turn latch, I had built some thin test pieces with the same cross-section as the flap grip – one with a plug, and one with a socket.  I did the same thing for the larger latching mechanism, so all I had to do was to put some mounting holes in the socket test piece and throw it in the box with the completed flap grip/caddy assembly.  John can mount the ‘garage’ in some convenient location in his cockpit, and simply latch the caddy assembly to the ‘garage’ after unlatching it from the flap grip.

Caddy Garage.  Note mounting holes for convenience

Caddy Garage. Note mounting holes for convenience

OK, off to the Post Office tomorrow to mail the new stuff to John.  I hope this new version will survive the ‘Gorilla Pilot’ test in better order than the last one did! 😉

Frank

 

TinkerCad vs 123d Design vs MeshMixer – Pick your Poison

I started into the 3D Printing world just a few months ago with a PrintrBot Metal 3D printer, a strong commitment to learn, and and very little else.  Since then I have spent countless hours with the printer and several different 3D CAD applications to design and instantiate various 3D designs.  In the process I have learned a LOT about AutoDesk’s Tinkercad, 123d Design, and MeshMixer applications. These are all free applications that purport to make it easy and intuitive to create 3D designs for 3D printing, and all three offer some amazing capabilities and features for free apps.  Unfortunately, it can also be very frustrating to discover that after many hours trying to incorporate some specific feature into your 3D design, ‘you can’t get there from here’ and you are left high and dry with nowhere to go.  MeshMixer is such a different program than either 123d Design or Tinkercad that I don’t plan to discuss it in this post – maybe later.

I have decided to coin the phrases ‘linear frustration’ and ‘Nonlinear frustration’ to describe the differences between 123d Design and Tinkercad.

Linear Frustration (aka Tinkercad)

Tinkercad is an absolutely amazing 3D design application.  It has a very intuitive GUI, and it takes almost no time to become proficient and productive with its very simple set of primitives along with a robust set of manipulation features (WorkPlane, Group/Ungroup, Adjust/Align, and Solid/Hole).  The Workplane concept is particularly powerful in that it allows you to quickly define the plane on which the next primitive will be placed and manipulated.  This makes it child’s play to construct fairly complex objects in rotated and/or displaced local coordinate systems.  Unfortunately, Tinkercad runs out of gas fairly quickly when designs require sophisticated treatment like morphing from one shape to another (an ellipse to a rounded rectangle in my case), or when reshaping objects after rotation.   This is what I refer to as a ‘Linearly Frustrating’ in that the problem isn’t so much a failure of the package as much as a limitation on how much you can do with the limited suite of primitives and manipulation tools offered.  Every tool does what it is supposed to, but the combination doesn’t allow an infinite pallet of options.  With added work and persistence you can go a LONG ways with Tinkercad, but eventually the law of diminishing returns will get to you and you’ll be looking for something else with more horsepower.

There are a couple of other frustrations with Tinkercad that have more to do with the way designs are stored and managed; I’m a complete neat-freak when it comes to project file organization, so this is a big deal for me.

  • although Tinkercad offer the ability to assign collections of designs to a ‘Project’ folder, all Tinkercad does is create a soft link from the corresponding design in the ‘All Design’ collection to the Project view. This means that if you happen to edit, or god forbid delete the ‘All Designs’ design, the ‘Project’ design gets deleted too – ouch!  The ‘Project’ idea is nice, but it is basically useless unless designs are copied to Project folders rather than just linked.
  • Along the same lines, there is apparently no way to copy or delete multiple designs at once.  I have over 150 designs now, but many of them are early versions that I no longer need; it would be pretty nice if I could multi-select designs for deletion.
  • And last, but not necessarily least – Tinkercad is apparently a victim of its own success, as the Tinkercad server(s) have been unreliable of late due (I think) to extremely high activity levels.  Maybe Autodesk should consider fixing some of the more egregious problems with 123D Design (see below) so more of us would move off Tinkercad and onto 123D Design ;-).

Non-Linear Frustration (aka 123d Design)

And along comes AutoDesk 123d Design… I swear this app represents Yin and Yang, Good and Evil, Blissful Marriage and Ugly Divorce, Superman and Kryptonite, Batman and The Joker and all the other polar opposites you can think of, wrapped into one super-powered but fatally flawed 3D design program

Whoever was in charge of implementing the GUI (Graphical User Interface) for 123d Design gets my vote for Evil of the Century.  The very first mouse-driven user interface was created back in the late 1960s by Douglas Engelbart, at Stanford Research Institute, and ever since then the GUI has been evolving.  It used to be that ‘bad’ GUIs abounded, with weird menu modalities and nonsensical procedural rules, but these evolutionary dead-ends have been mostly driven extinct.  GUI paradigms have now evolved to be nearly universal, to the point where humans can transition from one program to another with very little effort.  Everyone expects and demands top-level menus that are activated with a left click, context menus that are activated with a right-click, and so on.  Programs that don’t conform to that expectation immediately create a cognitive dissonance in the mind of the user, who now has to spend processing power just trying to figure out how to talk to the program, rather than how to transfer the 3D image in his/her brain onto the drawing canvas.  Imagine you have rented a car at some distant airport, and you discover that the steering wheel is connected to the wheels in such a way that turning the steering wheel to the right causes the road wheels to turn to the left, and vice versa.  It has been proven over and over again that it is virtually impossible for humans to recover from a crossed-control situation like this, even if they know up-front that the condition exists! This is because they have gotten so used to subconsciously controlling steering in one way that the car is off the roadway and into the ditch before the driver even realizes something is wrong.  Thus, a deeply embedded interface paradigm cannot be violated without extreme consequences.  In another context I had occasion to research the results of crossed rudder pedal control accidents in aviation.  What I found was that in every case of crossed rudder pedals, the pilot was unable to recover without crashing the plane, regardless of the experience  and/or expertise level of the pilot.  In most (but unfortunately not all) cases, the crash happened during the takeoff roll, usually without fatal results.  I belabor this topic to emphasize the dangers inherent in screwing with GUI paradigms just to be different or because the designer “has a better idea” – it may be ‘better’ but if it is too ‘different’, it will be perceived to be (and will be, in fact) worse!

In the case of 123d Design, I swear the application design team was divided into four different sections.

  1. The math team was from India, spoke only Hindi, and worked entirely using paper and pencil.  They devised elegant and (mostly) correct transformation algorithms for things like the spectacular ‘loft’ algorithm that allows a user to morph one 2D sketch into another one, and the chamfer/fillet feature.
  2.  The object-interface team was from Nepal, spoke only Tibetan, and used 1980s Micro-Vax machines with an early version of X-Windows to create the low-level screen widgets that expose object parameters to the user. While also mostly correct, these interface modalities died out right along with the Micro-Vax (and for a good reason!)
  3. The main GUI team was from Mars, spoke English learned from study of “I love Lucy” and “The Jetsons”, and programmed on the latest MARC (Martian Artistic Research Center) 3D design tablets (unfortunately for us humans, MARCs inherited their GUI paradigms from “The Jetsons” as well).
  4. The integration team was from AutoDesk, spoke Valley English, smoked pot on the weekends (and on the weekdays, and at lunch, and…) and were experts at putting lipstick on pigs.  They spent a few days and used up a 55-gallon drum of lipstick, and vioila-123d Design!
  5. The testing team – What testing team?

OK, OK it couldn’t possibly be that bad – I’m sure the Martians had access to other TV programs too ;-).

123d Design has some wonderful features (like the ‘loft’ feature) that can be a treat to use.  Unfortunately 123d Design is also one of those evil-ridden applications where you cannot make three mouse clicks in any one direction without falling into yet another devil-spawned GUI trap of one sort or another.  To mention just one or two:

  • You can non-linearly scale any 3-D object, but you can’t non-linearly scale a 2-D object, even though the non-linear scaling fields are exposed and can be edited!  It’s just that nothing happens when you do!  I would die from embarrassment if I had to admit I was part of a design/programming team that couldn’t even remember to connect all the numerical entry fields to their corresponding class variables – I mean c’mon guys!
  • When using the ‘Transformation’ (move/rotate) feature, there is a single numerical entry box presented to the user with no label.  One has to mouse over the box to find out what it does, and what it does changes depending on what axis you last clicked on!  So you could enter a number and discover it does exactly what you wanted – or not– depending on the recent past history of your mouse clicks.  You have to click on an axis, and then hover over the entry field to see if the hidden label now says the right thing.  This is more than stupid – it’s EVIL!
  • When you want to open a locally saved design file on the PC version of 123d Design, it takes 3 mouse clicks instead of the one click for every other application on the planet.  First you click on ‘Open’ (well, duh!) – but then you get a dialog urging you to “Sign In!” so AutoDesk can “Access Your Projects” – NOT!!  Then you have to click on the “Browse My Computer” tab, and then you have to click on ANOTHER ‘BROWSE’ BUTTON!! – grrrr.  And, you have to that every time you want open a design file on your own damned PC!!  No ‘Recent File List’, no MRU (Most Recently Used) exposure, nothing!  Even AutoDesk should be aware of the MRU concept by now!
  • The main window of the 123d Design PC version cannot be resized below a certain size, which occupies about 2/3W by 1/2H of the real estate on my 1920 x 1080 monitor.  No other application on my PC, and almost no other application I have dealt with over the last decade or so does this.  Can you say “f###ed up”?
  • It is apparently impossible to Ctrl-C/Ctrl-V an object from one 123d Design instance to another one on the same PC – a feature that has been in every multiple-instance application since Gates and Jobs were in diapers.  In order to copy a single object to another 123d Design instance, you have to save the file containing the object, open that file in the new instance, and then delete everything but the object you wanted to copy.
  • There’s no File Save As… menu selection; instead you have ‘Save’ and ‘Save a Copy…’, which has ‘To My Projects…’ and ‘To My Computer’ sub-menu choices – argghhh!
  • Ctrl-A doesn’t select everything – give me a break!
  • There is NO ALIGNMENT FEATURE!  you can group objects, you can arrange objects in circles, lines, or the Ohio State ‘Block O’ for all I know, but you cannot align them!  What kind of drawing program doesn’t have an alignment feature?  Rumor has it that the wonderful Tinkercad alignment paradigm has found its way into the iPad version of 123d Design, but not into the Windows version – the one used by about 70% of the 3D designers in the world.
  • There is no HELP!  There are lots of YouTube videos showing how to do this or that, but most were done with significantly (sometimes radically) different GUI’s from earlier versions.  Also, the videos ‘cherry-pick’ the features they like and avoid the features that don’t work (and they are legion!).
  • The help forum sucks big time; there are at least two different forum views, and I haven’t been able to figure out which view comes up when.  Posting questions or problems is a real nightmare, and there is the infamous problem where you can write up a long post only to be confronted at the end with an error message that says ‘You can’t submit this post because you haven’t yet logged in – please log in and we’ll bring you back to this page (and if you believe that we have a bridge we’d like to sell you)”.  Every other forum package on the planet puts up the ‘not logged in’ error message up front, or even better, simply disables the ‘Post’ button if you aren’t logged in!  And, if you do manage to finally get your post submitted, you’ll not find anyone on the other side of the curtain; Posts there have been unanswered for months if not years.

You may say that these are trivial gripes – and I would agree with you.  Except the same sort of passive/aggressive “I know better than the rest of the universe and you can do it my way or the highway and by the way, my way doesn’t even work half the time” behavior is rampant throughout the program.  So, instead of getting nice and warm and cozy with the program, my relationship with 123d Design is more like a series of running battles; I know I’m going to take casualties, but I need that particular feature and I have to hope I won’t get my ass completely shot off (this time) in the process.

Where to go from here?

Some posters on this subject have suggested that Autodesk has deliberately released 123d Design with such major and obvious flaws to get users hooked on 3D design so they can be sold their paid products like Fusion 360; sorta like giving away introductory heroin doses to capture more addicts.  My personal opinion is more like ‘Hanlon’s Razor’ – “Never attribute to malice that which is adequately explained by stupidity”.

 

ClearNav Joystick Part 7 – Flap Grip Model Finished? – NOT!

The title of my last post on this subject had the word ‘Finished?’ with a question mark, because I suspected that John and I weren’t really ‘finished’ with this project (and for that matter, may never be!), and sure ’nuff, the ‘finished’ version came back to me with some suggestions for improvements.  However, as has happened at every stage of this journey, lessons learned with each trial opened up avenues for improvement.  One of the many cool things about the current 3D printing world is that a single individual or a small group (in our case, a ‘group’ of two!) can traverse the complete trial, re-design and re-implement cycle in a very short time at essentially zero cost.  This short cycle time and low incremental cost means that failure isn’t only an option – it’s an expected and accepted way of rapidly stepping through many design variations in the quest for truly useful and cool ‘things’.  After all, who would have thought that a clay model of a joystick-mounted ClearNav remote caddy created by one pilot long ago would have evolved so rapidly into a detachable and rotatable flap handle mounted caddy at all, much less in the 2-3 months we have been working on the project (and this time includes several ship/return cycles to move trial pieces from my lab to John’s glider and back again!).

So, anyway, back to the current design cycle:  At the conclusion of last week’s episode, I had completed a new version and sent it off to John for testing.  This version included the following improvements:

  • Deleted the cable channel in the flap grip piece
  • Resized the rectangular slot in the flap grip piece
  • Removed the finger scallops on the front of the grip
  • Offset the caddy piece slightly forward of the flap handle centerline, and rotated it about 20 degrees ‘up’ relative to the top surface of the flap grip
  • Used a round vs rectangular post to couple the caddy to the flap grip to allow for rotation
  • Added protection walls for the RJ-11 remote connector

Although this version was a decided improvement over the last one, I still wasn’t happy with it, for a number of reasons:

  • First and foremost – the way that I had implemented the rotation feature meant that John could no longer remove just the caddy portion from the flap grip when entering/exiting; now he had to remove the entire system, flap grip and all, from the flap control bar.  I didn’t think this would work as a long-term solution.
  • The transition piece from the flap grip ellipse to the remote caddy rounded rectangle was clunky and ugly, to say the least

So, even as the previous version was on its way down to John, I was already working on ideas for the next version to address the above issues.

Rotatable and Detachable:

I wanted a way to have my cake and eat it too – a way to make the remote caddy easily (and repeatedly) detachable from the flap grip and easily rotatable about the axis of the flap grip and fixable at the desired rotation angle.  Whatever solution I came up with had to also be implementable as a plastic 3D-printable shape – no cheating allowed!

Option 1 – Snap Ring:  Maybe I could design a snap ring setup, where the post on the bottom of the caddy piece would snap into some sort of groove in the flap grip so it would rotate freely but not just fall out – some force would be required to detach it?  I decided to experiment with this a bit and see if I could come up with something workable.  Another of the many cool aspects of 3D printing is that I can rapidly design and print small parts to test just the current idea, without wasting time with non-relevant structures.  In this case, I designed and printed several pairs of ‘buttons’ just to test the snap ring idea.

Female snap ring 'button'

Female snap ring ‘button’

Male snap ring 'button'

Male snap ring ‘button’

Connected snap ring buttons

Connected snap ring buttons

What I learned from this series of experiments is that a) I’m not that good of a Mechanical Engineer, and b) The snap ring idea is great for a semi-permanent rotational coupling, but not so much for a system that must be connected and disconnected many times. The plastic is just too hard – it’s just as likely that the part will fail before the snap ring disconnects!  The good news is that I was able to learn this lesson quickly and cheaply! ;-).

Option 2 – Separate the rotation feature from the attach/detach feature:  The snap ring exercise convinced me that I needed to separate the rotation feature from the attach/detach feature.  Conceptually, this meant that I had to partition the system into three parts rather than two; the flap grip, a ‘converter’ piece that would attach/detach from the flap grip on one side, and would form a rotational surface with the remote caddy piece on the other, and the caddy piece itself.  Separating the design into three pieces vs two wasn’t really much of a conceptual leap anyway, as I had already done most of this in the previous incarnation when I used the 123D Design’s ‘Loft’ feature to transition from the flap grip ellipse to the caddy rectangle.  All I had to do was to make that transition into it’s own separate piece, with some sort of attach/detach mechanism on the bottom, and a rotation feature on the top.  Of course I still had to figure out what those mechanisms were, but details, details, details! ;-).

Quarter-Turn Latch For Attach-Detach:  While I was doodling around trying to figure out a good mechanism for latching/unlatching the center ‘converter’ section to the flap grip, my wife happened to look over my shoulder and casually say “what about a quarter-turn fastener?”.  My first thought was “nah – WAY too hard”, but the more I though about it, the more is seemed like that might not be such a crazy idea after all.  One of the many cool things about 3D printing is its ability to form internal structures that aren’t possible via normal milling/machining techniques, another is its ability to convert a solid shape to a cavity and vice-versa, and another is the way it facilitates rapid experimentation.  The combination of these three things allowed me to design complementary plug/socket designs, and then rapidly iterate through several versions to improve the design.

I started with a circular base for both the ‘plug’ and ‘socket’ version of the quarter-turn latching mechanism, but rapidly changed to an elliptical base that exactly matched the cross-section of the flap grip. I knew I would eventually need to transfer the mechanism to the top of the flap grip and the bottom of the identically-shaped bottom of the center transition section, so using the same shape for the experimental parts would make the transfer a LOT easier.  The first set of trials were pretty clumsy, as I had no real idea what a good mechanism looked like, how to determine the amount of rotation from locked to unlocked, and which direction I wanted the locking rotation to go.  Version 1 used a rectangular tongue for the latch, but I discovered this didn’t work very well, so this evolved to a pie-section tongue shape, and the complementary internal socket channel evolved to match.

Version 1 of the quarter-turn fastener socket

Version 1 of the quarter-turn fastener socket

Version 1 of the quarter-turn fastener plug

Version 1 of the quarter-turn fastener plug

Version 3 of the quarter-turn latching mechanism

Version 3 of the quarter-turn latching mechanism

Version 3 of the quarter-turn latching mechanism with internal details shown

Version 3 of the quarter-turn latching mechanism with internal details shown

By version 3, I had also started adding ‘engraved’ version number and orientation reference marks to the experimental pieces as an aid for getting the lock/unlock orientations right (after having screwed this up a couple of times without the reference marks).  I had also gotten smart enough (after some more screwups) to extract the design of the quarter-turn mechanism into its own file, so it could be added to whatever structure required it (and making it available for completely different future projects!).

Version 2 and V3 plug/socket parts in their own design file

Version 2 and V3 plug/socket parts in their own design file

Doing this made it MUCH easier, for instance, to reverse the lock/unlock rotation direction when I discovered that the original orientation made the mechanism too easy to unlock inadvertently during normal use (50/50 chance and I blew it – again!).  The finished (as much as anything gets finished in this project) product is shown below

FlapGrip to center section quarter-turn locking mechanism.

FlapGrip to center section quarter-turn locking mechanism.

Center section in the locked position on the flap grip

Center section in the locked position on the flap grip

Center section in the UNlocked position on the flap grip

Center section in the UNlocked position on the flap grip

Rotational Feature:  Based on earlier feedback from John, I wanted the remote caddy to be able to rotate with respect to the flap grip.  In an earlier incantation, the piece that transitioned from the flap grip ellipse to the semi-rectangular remote caddy was integrated into the remote caddy, and the entire piece rotated about the top of the flap grip.  This was OK, but the transition/caddy section could not be easily removed from the flap grip, making glider entry/exit potentially awkward.  In the new setup the idea was to separate the transition section from the remote caddy so it could rotate around the top of the transition section, while the combined caddy/transition sections would attach/detach from the flap grip via the quarter-turn fastener.  So, I needed a rotation mechanism, preferably with some sort of detent arrangement so John could try different rotation angles in flight.  The detent requirement led to another series of experiments with snap-ring buttons, with a small protruding tip one button that engaged a set of radially distributed grooves on the other.  The result, unfortunately, was that if the tip was sufficiently large to properly engage the grooves, it was also large enough to  make it nearly impossible to ‘click’ from one groove to another.  In other words, it turned out to be pretty much an ‘all or nothing’ kind of thing.  Fortunately I still had a couple of the McMaster-Carr ball-spring plungers left over from the last go-around, and I replacing the protruding tip with a spring-loaded ball did the trick very nicely!

Remote caddy interior details showing rotation and detent arrangement

Remote caddy interior details showing rotation and detent arrangement

Remote caddy bottom surface showing detents

Remote caddy bottom surface showing detents.  Note the ball-spring plunger in the top of the transition piece

OK, so now we had the desired quick-release feature so John can easily remove the remote caddy (with its attached cable to the ClearNav) from the flap grip for glider entry/exit, AND the desired ability to rotate the caddy with respect to the flap grip axis!  All it took was a little persistence, a genius wife, and about a million design/implement/test cycles ;-).  The following photos show the various experimental parts generated, and the ‘final product’ (but of course, ‘final product is what I said the last time!)

 

Collection of experimental printed parts

Collection of experimental printed parts

Disassembled system showing all three pieces

Disassembled system showing all three pieces

Assembled 3-piece system

Assembled 3-piece system

Stay Tuned!

Frank

 

 

 

 

 

 

 

 

ClearNav Joystick Part 6 – Flap Grip Model Finished?

In Part 5 of this journey, I described our paradigm shift from a joystick mounted ClearNav remote caddy to a flap grip mounted version.  When John received and tested the first try at this approach, he agreed we were on the right track, but there were some ‘issues’ (there are *always* issues!).

  • The cable channel in the flap grip piece is unusable, as routing the cable this way interferes with opening the canopy.  Instead, John just used the single tie point on the caddy piece, and simply detached that piece when entering/exiting the glider
  • The rectangular slot in the flap grip piece was a bit too roomy in the forward/aft direction.
  • The finger scallops on the front of the grip didn’t really fit John’s fingers – oops!
  • The caddy piece would work better if it was offset slightly forward of the flap handle centerline, and rotated about 20 degrees ‘up’ relative to the top surface of the flap grip (i.e. toward the glider centerline)
  • The way that the caddy piece was attached to the flap grip prevented it from being rotated slightly to accommodate John’s actual thumb position; he suggested a round stud rather than a rectangular one.
  • The remote connector (a RJ-11 phone-style connector) sticks out the front of the caddy and is vulnerable to damage; John suggested I design in some protective walls for this.

Incorporating all the above elements into a new design involved some head-scratching, and quite a few 4-letter words, as I found that none of the 3D design tools I have so far employed (TinkerCad, 123D Design, and MeshMixer) would do the whole job.  I wound up working with all of them at one point or another in order to get what I wanted.  In addition, I was in the process of upgrading my PrintrBot 3D printer with a heated bed to accommodate future plans to print with ABS plastic in addition to PLA, and this turned out to be a lot more complicated than I had envisaged (I eventually reverted to my original hardware configuration, as I could not get consistent prints with the heated bed).

The first three items above were trivial to solve – just deleting the relevant ‘hole’ structures from the design, and modifying the rectangular slot dimension slightly.

The last three, however, required a complete re-thinking of the way the caddy piece coupled to the top of the flap grip piece.  The flap grip has an elliptical cross-section, with a top surface that is parallel to the glider centerline, while the caddy piece has a rectangular cross-section that needed to be tilted up 20 degrees to the flap grip piece.  In addition, the front portion of the caddy piece needed to have significant material added to support a side wall protection structure for the RJ-11 connector.  I ran through several TinkerCad versions but ultimately realized that TinkerCad just kind ran out of horsepower to handle the complex surface morphing I was looking for.  I just couldn’t get any kind of a smooth transition from the elliptical flap grip shape to the essentially rectangular caddy shape *and* provide for connector walls.

 

An early concept for the 'new improved' flap grip model

An early concept for the ‘new improved’ flap grip model

An early concept for the 'new improved' flap grip model

An early concept for the ‘new improved’ flap grip model

However, I had been playing with 123D Design as a possible alternative to TinkerCad, and realized that it’s ‘sketch lofting’ feature might be just what I needed (assuming I could get past all the 123D Design frustrations and actually make the *%$@!#%$#* thing work!  The way the ‘lofting’ feature works is to take a ‘base’ 2D sketch in an X-Y plane (in my case, an ellipse representing the top of the flap grip), and morph it into a ‘top’ 2D sketch (an outline representing the bottom of the caddy section) over the Z-axis distance between the two sketches.  By doing this I hoped to get a much smoother transition from one surface to the other.  After playing around with this in 123D design for a while, I actually got this feature to work (an unusual occurrence with this program!). The following two images show the basics of the feature – here I have ‘lofted’ an ellipse in the Z=0 plane to a rectangle in the Z=50 plane, rotated about the Y-axis by 20 degrees.

2 different 2D surfaces

2 different 2D surfaces

An ellipse 'lofted' into a tilted rectangle

An ellipse ‘lofted’ into a tilted rectangle

For my purposes, I imported the flap grip and caddy pieces into 123D Design, and used them as patterns for the required 2D sketches.  I still needed to add the connector-guard section onto the front of the caddy section sketch, but this was fairly straightforward using the 123D Design ‘2D polyline’ feature.  Once I had the two surfaces mapped out and placed at the desired heights/angles, I could use the ‘loft’ feature to create a transitional 3D structure.  The first run at this is shown in the following screenshot.

First try at blending the flap grip surface to the caddy surface

First try at blending the flap grip surface to the caddy surface.

This actually worked pretty well, but I realized that the connector-guard portion of the transition structure wasn’t going to be nearly deep enough (in the Z-axis direction) to actually do any connector guarding – bummer!  So I tried again using a 3-surface model, with a middle surface using the non-rotated caddy outline plus the outline of the connector guard.  With this setup, I got a much more radical initial transformation from the ellipse to the caddy outline (not so good), but much more available bulk in the Z-axis direction for the connector guard (very good).  On balance, the need for the additional connector guard material outweighed the aesthetics of the smoother transition, so I wound up with a transition section that looked a bit like some prehistoric alligator (minus the legs) but…

More or less final transition section from the flap grip ellipse to the caddy

More or less final transition section from the flap grip ellipse to the caddy

Caddy, transition section, and cylindrical mating stud

Caddy, transition section, and cylindrical mating stud

The next step was to import the transition section created in 123D Design back into TinkerCad for additional work and tuneup prior to 3D printing.  It was right in here somewhere that TinkerCad (a ‘cloud-based’ application) mysteriously went away for about 24 hours, causing a major hiccup in my project and correspondingly major damage to my Wa (I had upwards of 80 design revisions in the TinkerCad cloud, and if they all went away…).  Fortunately for me and my Wa, TinkerCad came back several hours later, and I was back in business.  The following screenshots show the ‘final’ (as if this project will ever end!) version of the remote caddy section.  The holes in the remote caddy bed were intended to accommodate the remote’s mounting screws (so they could be retained in the remote and not lost), but unfortunately the measurements were a bit off :-(.  The side view shows the tie-wrap attachment ring on the front undersurface, and the mounting plug on the bottom.  Both the mounting plug and the front portion of the caddy underside were shaved off a bit to create a larger attachment area for 3D printing

Final caddy version side view.  Mating plug and front bottom portion shaved off for better 3D printing

Final caddy version side view. Mating plug and front bottom portion shaved off for better 3D printing

Final remote caddy version.  Note holes for remote mounting screws (didn't work)

Final remote caddy version. Note holes for remote mounting screws (didn’t work)

So now it was time to fire up my 3D printer and start making parts.  Unfortunately, in the interim between this version and the last one I had decided to do the long-awaited upgrade to a heated print bed so I could eventually transition to stronger and more resilient ABS plastic instead of only PLA.  The downside to a heated print bed is the much higher power requirements, and a host of other secondary problems associated with heated-bed printing.  As it turned out, I couldn’t get a consistent print of the caddy piece with ABS or PLA using the heated bed, so I eventually had to downgrade my hardware setup and revert back to the original unheated bed, at least for these prints.  The following screenshot shows the problem with PLA on the heated bed.  The heat from the bed causes the PLA filament to stay soft too long and curl upward, even with forced air cooling.

An aborted attempt at printing the remote caddy piece.  Note the curled up edges and numerous print failures

An aborted attempt at printing the remote caddy piece. Note the curled up edges and numerous print failures

Anyway, after getting the hardware restored to its original unheated configuration, I started making trial prints of the remote caddy.  The first several tries were failures for one reason or another.  The first few trials failed because I had inadvertently disabled the ‘generate support structures’ option, and the next few failed because the support structures, when enabled, were too tightly bound to the main structure to remove when the print was finished!  It took some tweaking and print re-orientation to get to a configuration that produced useful results, although I’m still not happy with the ‘final’ (see above) product.   After the caddy piece, the flap grip piece was “a piece of cake”, as its geometry was much less complicated, although physically much bigger.  The final caddy piece took about 1.5 hours to print, while the flap grip piece went for more than 4 hours!

 

After getting both parts printed, there was still quite a bit of work to be done, especially on the caddy piece.  As it turned out, the cylindrical post on the bottom of the caddy piece was much too long for the matching hole in the top of the flap grip (measurement goof on my part), so the post had to be cut down by hand.  Then I had to drill and tap the post for a 4-40 screw so John can tighten the caddy down on the flap grip when he gets the rotation angle correct for his hand placement.  Then a 4-40 clearance hole had to be put into the top of the flap grip piece, and the 4-40 screw threaded up into the rectangular slot, through the clearance hole, and then screwed into the caddy mounting post (let’s hear it for double-sided tape and long, skinny screwdrivers!).  Also, the bottom surface of the caddy was a lot rougher than I liked (printer misconfiguration?) so I had to spend some time with a file and a sanding block to get this surface even remotely acceptable.  I think I’ll try some more experiments to see if I can do a better job at this, so I’ll be ready when John comes back with the next batch of ‘issues’! ;-).

Stay tuned!

Frank

 

 

 

 

 

 

ClearNav Joystick Part 5 – Back to the Drawing Board Again Again

The ‘minimalist’ joystick model from Part 4 was barely out the door before I had another brainstorm.  I have always done some of my best thinking while in bed, waiting for sleep to come.  My brain is still going over the events of the day, teasing at unsolved problems, and sometimes just as I’m about to drop off, a possible solution or different approach to a problem becomes clear.

In this particular case, it occurred to me that the joystick might not be the best place for a remote control caddy – maybe it would be better on the flap handle instead! This was such a powerful idea that I practically leaped out of bed, padded barefoot down the hall to my office/laboratory, wrote “Flap Handle!” on a post-it note and stuck it to my primary PC monitor.  In the light of the next day, awake, alert, and with coffee in hand the idea seemed even better.

Pros:

  • In a flapped ship, the pilot’s left hand is almost always on the flap handle, and there aren’t any other controls or switches there to interfere with a remote control pad.
  • The flap handle is on the side of the glider, so wire routing should be easier.
  • Flap handle mechanical motion is also much more constrained than joystick movement, so interference with other cockpit objects/controls becomes a non-issue.
  • Button actuation with the left thumb should be much easier, assuming the CN remote caddy could be angled correctly with respect to the flap handle.

Cons:

  • The flap handle juts out over the pilot’s left leg, so anything mounted to the end of the flap handle is vulnerable to damage as the pilot gets into or out of the glider
  • The cable from the remote control to the ClearNav (CN) has to get from the end of the flap handle to the side of the glider somehow, and the length of the cable run to the CN changes significantly with the forward and aft motion of the flap control
  • Getting the right caddy/flap handle relative orientation might be tricky.

A completely independent, but quite significant ‘Pro’ for this idea was that it offered a perfect vehicle to demonstrate the power and flexibility of the 3D printing paradigm to my two grand-children (and their parents) who happened to be visiting over the Labor Day weekend.  As it turned out, Danny (12 years old  and younger of the two) dived in with great enthusiasm, and by the end of his stay was doing design modifications on his own!

When I broached this idea to my friend, he was also enthusiastic, and sent photos detailing the flap handle dimensions and a photo with the remote control held in what he thought might be the correct orientation.

 

Armed with this information, Danny and I started work.  The overall strategy was to constuct a new handle, shaped more or less like the old one, but with the CN remote caddy section from the previous ‘minimalist’ joystick grip design (see Part IV) attached to the end at an orientation approximating the one shown above.

The first thing I did was to take a short trip to the local hardware store and purchase a 3′ section of 1″ x 1/4″ aluminum flat stock, slightly larger in both dimensions than the actual flap  handle.  I figured we could use this for initial hole sizing/testing, and adjust later if necessary.  Next we designed and printed a test piece to confirm we had the rectangular hole size correct (we did).   Next we started designing the replacement handle, incorporating the slot from the above test piece.  Somewhere this step, we inadvertently scaled the handle and its internal slot down by a factor of about 2/3, so the first couple of handle prints came out way undersized.  Fortunately, we were watching the print as it built up from the bottom, so we recognized the problem pretty quickly and aborted the print after 1/4″ or so.  This actually turned out to be a pretty cool technique; we would make a full-length design, but only print a few mm or so, as the cross-section was more or less uniform throughout.   As we got closer to what we thought would be a final design, we would let the print continue longer, finally letting the print go to completion.  This way we could iterate much faster, and save filament too! ;-).

By about Rev 3 we had a full-sized constant-cross-section cylindrical flap handle printed up that we could slide onto the metal flap handle simulator, but we soon determined it was way undersized for an adult hand (it fit Danny, but…).  So, back to TinkerCad for more revisions.  Along the way, we also tried out some ideas for creating finger-grip indentations on the front side of the grip, and a corresponding palm indentation on the back side.  As it turned out, we were able to use TinkerCad’s ‘Round Roof’ (a semi-cylinder) object for both – at a small scale for each finger indentation, and at a larger scale for the palm indentation.

Basic flap handle grip with finger and palm indentations

Basic flap handle grip with finger and palm indentations

So now we had a basic flap handle grip, with finger and palm indentations and a rectangular hole for the flap handle.  We still needed a way to attach the CN remote caddy to the end, and we needed some way of getting the control cable down the flap handle to the side of the glider.  Our first run at this was a cylindrical cutout in the side of the grip.  The idea was that the control cable could be pressed into the cutout through a small gap in the side of the grip, but wouldn’t come back out again without some effort, thus allowing for a smaller diameter hole because the end connectors (telephone style RJ-11’s) wouldn’t have to be accommodated.  This was an OK idea in theory, but in practice we were stymied by a limitation in the ‘slicing’ software that converts the solid object model into thin wafer-slices that the 3D printer can handle.  The slicer software kept opening up the gap to the point where the cable wasn’t retained – it would just fall right back out again.  So, we took a closer look at the connectors and determined that although a 12 mm round hole would be required, we could get away with a 9 x 9 mm square hole!  The smaller square hole dimensions would allow us to put the hole entirely inside the flap grip and still not interfere with the main rectangular hole for the flap handle itself – ah, the wonders of 3D printing! ;-).

Next we tackled the problem of how to connect the CN remote caddy section from the ‘minimalist’ joystick grip model (See Part IV) to the flap handle grip.  We decided that if we carried the rectangular flap handle hole all the way through the grip, and made the grip a bit longer than the actual handle, we could use the hole as a socket, and make a corresponding ‘plug’ section that would mate with the CN caddy.  We created the ‘plug’ section by simply slicing off about 1/4″ of the handle into its own part, changing the rectangular hole to a rectangular solid, and then mating that part with the CN remote caddy.  However, we quickly discovered that while it would be possible to print the combined part, it would be ugly, as the combination would require an exorbitant amount of support material due to the weird mating angle.  So, we sliced and diced yet again, and printed the plug and caddy sections as independent parts (although we did print them at the same time) and glue the two together post-print.  As it turned out, the first revision of the plug didn’t have a big enough indentation for the caddy, so the resultant piece wasn’t strong enough.  Back to TinkerCad, where we extended the plug a bit to provide more ‘meat’ for the mating interface.  This also necessitated a slight modification to the design of the cord handling tunnel, as it had to be ‘bent’ slightly at the end to allow the cord to be threaded behind the remote caddy and into the tunnel.

TinkerCad drawing for the CN caddy plug with large indent

TinkerCad drawing for the CN caddy plug with large indent

'Small Indent' and 'Large Indent' caddy plug versions

‘Small Indent’ and ‘Large Indent’ caddy plug versions

At this point we had designed and printed all the required pieces – the flap handle grip, the ‘plug’ to connect the grip to the remote caddy, and the caddy itself.  All that remained was to glue the caddy to the plug (which turned out to be a mini-project in itself) and get the two pieces (caddy/plug and grip) down to John for him to try out on the actual glider.  Stay tuned for the results! ;-).

As a not-insignificant side note to this project, my 12 year-old grandson got a great introduction to the world of 3D printing, and quickly became as much a participant as a spectator.  The TinkerCad software GUI is very intuitive, and easily passed the 12 year-old usability test.  By the end of his 2-day stay with us, he was designing parts in TinkerCad, downloading the STL files to my Linux box, and running my PrintrBot printer to actually print the parts, all with little or no supervision on my part.  In fact, the only thing Danny had real trouble with was getting the printed parts off the print bed (protected by blue painter’s tape)  because that required a bit more strength and precision with the removal tool (wood chisel with a 1/2″ blade) than he was able to muster.

Frank

 

ClearNav Joystick Part 4 – Back to the Drawing Board Again

Part 3 described a ‘back to the drawing board’ approach to the ClearNav remote caddy joystick grip project. That effort resulted in a cylindrical grip with the CN caddy from the clay model grafted on.  This worked out OK, but it didn’t look very pretty – it was a bit asymmetric, and I never got the surface smoothness I wanted on the caddy section – it was kind of lumpy and irregular.

So, I went back into MeshMixer and spent some quality time figuring out how to use the sculpting tools more effectively.  The documentation for all of the Autodesk 123 products (and TinkerCad too) is almost non-existent, so the only way I have found to learn how to use the various tools is by trolling for the few (and also now outdated) YouTube videos and by brute-force experimentation.  Anyway, after many hours of playing around, I figured out how to do such things as combining MeshMixer-provided primitive shapes with my clay model derived CN caddy section, and how to use the ‘attract’ sculpting tool to regularize surfaces – very neat!!  I was ultimately able to combine both a rectilinear solid and a torus into something that was a lot more regular, and may well have formed the basis for a successful CN remote caddy grip.  However, as I was doing all this (and learning a LOT), it occurred to me that I was once again going about this the hard way….

 

It finally occurred to me that if all I wanted was a minimal CN remote caddy, I already had one!  Early on in the project I constructed a blank plug using TinkerCad and working off the dimensions from an old CN remote I had laying around the house.  All I had to do to create a ‘minimalist’ caddy would be to expand this plug a few mm in all directions, and then put a plug-sized hole in the middle of it.

CN Remote plug constructed early on in the project

CN Remote plug constructed early on in the project

So, I copy/pasted the above plug into a new TinkerCad design, expanded it as described above, and mated the result with the cylinder grip from Part 3, as shown below.

 

Minimal CN remote grip with caddy cavity and CN remote shown

Minimal CN remote grip with caddy cavity and CN remote shown.  Note the cable management loop about halfway down the grip cylinder

Top view showing CN remote installed on minimal grip

Top view showing CN remote installed on minimal grip.  Note the cable management loop about halfway down the grip cylinder

Side view showing CN remote installed

Side view showing CN remote installed.  Note the two cable management loops built into the design.

Side view showing CN remote cable and cable management loops

Side view showing CN remote cable and cable management loops

On all the previous designs, the plan was to utilize the ClearNav stick-top remote accessory rather than the fob-mounted style, as the fob style has a telephone-style connector on the front to connect the cable that goes from the remote to the ClearNav itself.  On this ‘minimalist’ design it occurred to me that I could do away with that requirement by putting a slot in the front of the caddy section to accept the phone jack, and adding a couple of cable management loops to the grip body.  In this way the user could simply detach the remote from the fob and press it into the caddy cavity, and presto – instant stick-top remote!

A complication with this plan is that the CN stick-top remote accessory comes equipped with an integrated PTT switch, as the stick top remote assembly typically takes over the real estate formerly used by the original PTT button.  Since the ‘minimalist’ design doesn’t do that, the user can simply re-use the original PTT button. To facilitate this, I put a small pilot hole in the top center of the cylinder.  I used a pilot hole here because I don’t know the diameter of the original switch.

Anyhoo, this design was shipped off to my friend yesterday, for its date with reality.  I have high hopes for this one, but who knows?  Stay tuned! 😉

Frank

 

ClearNav Joystick Part 3 – Back to the Drawing Board

At the conclusion of Part 2, I had a finished design and a finished 3D part, which I sent off to my friend for evaluation in his glider.  Unfortunately, the evaluation was – “It sticks up too high, and hits my stalk-mounted ClearNav unit”  After going through some back-and-forth, he sent me some photos to illustrate the problem.  The original rubber stick grip with top-mounted PTT switch just clears the bottom of the ClearNav (CN) unit, so anything higher than the original is going to be a problem.  The finished grip I created based on the clay model was, unfortunately, about 2″ too high :-(.

So, back to the drawing board.  I tried a ‘shorty’ version of the original grip, but that only got me about 1″ of the needed 2″ or so height reduction, so that was out.  Then I decided to throw the entire clay model derived design out the window, except for just the CN remote caddy portion, and start over from there.  The problem with the original clay model design was that it was slanted in such a way that it could not slip all the way down onto the stick, so I decided to start with a simply cylindrical grip that would slide completely down onto the stick, and then somehow tack the CN remote caddy onto the front.

Cockpit photos showed that the vertical portion of the joystick was about 4″ long, including the trim release trigger, so I started with a cylinder of a little over 100mm.  This cylinder would house the hole for the stick, so it would obviously have to be bigger than the stick diameter of 25mm, plus some additional wall thickness.  How much bigger?  I decided make it just big enough to completely sever the CN remote caddy portion from the rest of the ‘finished’ grip derived from the clay model.  I started this process in TinkerCad by placing a cylindrical ‘hole’ in the model, and increasing its diameter until it just stuck out of both sides of the model at the neck, separating the front and back halves.  This required a cylinder diameter of 35mm, as shown below.

Separating the CN remote caddy from the rest of the grip

Separating the CN remote caddy from the rest of the grip

Removing the rest of the grip from the design

Removing the rest of the grip from the design

After that, I added a rectangular ‘hole’ to remove the now-separated back half of the grip, leaving only the CN remote caddy portion with a 35mm-diameter arc in the back.  Then I simply added a 35mm diameter solid cylinder to the design in the same place as the ‘hole’, and of course this cylinder fit perfectly into the arc made earlier by the 35mm diameter ‘hole’.  The only thing left to do was to ‘drill’ a 25mm hole into this grip cylinder, leaving a 5mm wall on the sides, and a 3mm wall at the top.  Assuming this grip arrangement was seated fully on the stick, then it should stick up no more than 3mm from the top of the stick itself, or less than the height of the original grip plus PTT switch.

This design is nowhere near as elegant as the clay model derived one, but it should work as a practical starting point for a design that actually works – the elegance can come later!

As a side note on all of this, the process of going from the original design to the ‘cylindrical grip’ design was very interesting because it is completely and utterly different than normal design practices.  Instead of building another design up from scratch, I was able to add just two ‘holes’ and one hollow cylinder to the original design to come up with something completely different.  In TinkerCad, you can add and combine solid parts, but you can also remove material by adding ‘holes’.  Every primitive in TinkerCad can be used as either a solid object that adds material to the design, or as a ‘hole’ that removes material from the design.  Moreover, portions of a design removed by holes don’t get removed until grouped with that hole.  Material that is removed via the addition of a hole isn’t really deleted – it is just ‘hidden’ by whatever combination of holes negates its presence (exporting the design as an STL file and then re-importing it into TinkerCad does, in fact, permanently remove all ‘holed’ portions of the design).  This process leads to some bizarre and counter-intuitive results, as it the order in which holes and solids are grouped determines the final visible result.  In a complex design, it is quite possible to wind up with an unexpected result, because the grouping order got changed somewhere along the way.  If the grouping error occurs down inside the design, then it might not get noticed until the 3D part is printed, and a hole that was supposed to be there isn’t, or some material that wasn’t supposed to be there suddenly reappears!

OK, so this design will go off to my friend tomorrow for yet another clash with reality.  Hopefully this one will be a little closer to usable, and maybe point the way toward a final product – we’ll see!

Frank